Albumin diffusivity coefficient estimation in imitated porous structure of interstitial space by integration of albumin diffusion model (ADM) to electrical impedance tomography (EIT)

Abstract

Albumin diffusivity coefficient D_I^a in imitated porous structure of interstitial space has been estimated by the integration of albumin diffusion model (ADM) to electrical impedance tomography (EIT) (iADM-EIT) under five different porosity Φ conditions (from Φ₁ = 0.922 to Φ₅ = 0.990) for transport phenomena quantification due to albumin-rich-fluid accumulation. The iADM-EIT is conducted by applying an iterative curve-fitting between spatio-temporal albumin concentration C_I^a derived from ADM and spatio-temporal distribution of time-difference conductivity Δσ reconstructed by EIT. The essential point of the iADM-EIT is the quantification of experimental C_I^a_ex from Δσ by establishing a constitutive relationship among C_I^a_ex, Δσ, and Φ. ADM is developed based on Fick's second law implemented in Krogh tissue cylinder. EIT is performed to image the Δσ caused by increase of C_I^a due to albumin diffusion phenomenon from a capillary to the imitated porous structure. The imitated porous structure is manufactured with agarose gels in a dynamic phantom including a capillary. As the results, the relative albumin diffusivity coefficient D_I^a/D₀^a (D₀^a: Albumin free diffusivity coefficient) is increased with increase of Φ in the range from 0.271 to 0.694, which are correspondent to the literature data with percent average relative error δ = 6.83±2.72 %.